Chemical Genetics Reveals a Role of dCTP Pyrophosphatase 1 in Wnt Signaling

Cell‐based screening is a powerful approach to identify novel chemical modulators and biological components of relevant biological processes. The canonical Wnt pathway is essential for normal embryonic development and tissue homeostasis, and its deregulation plays a crucial role in carcinogenesis. Therefore, the identification of new pathway members and regulators is of significant interest. By means of a cell‐based assay monitoring Wnt signaling we identified the pyrrolocoumarin Pyrcoumin as inhibitor of canonical Wnt signaling. Target identification and validation revealed that Pyrcoumin is a competitive inhibitor of dCTP pyrophosphatase 1 (dCTPP1). We demonstrate a yet unknown interaction of dCTPP1 with ubiquitin carboxyl‐terminal hydrolase (USP7) that is counteracted by dCTPP1 inhibitors. These findings indicate that dCTPP1 plays a role in regulation of Wnt/β‐catenin signaling most likely through a direct interaction with USP7. Ein zellbasiertes Screening für Inhibitoren des kanonischen Wnt‐Signalwegs identifizierte das Pyrrolocoumarin Pyrcoumin, einen neuen kompetitiven Inhibitor der dCTP‐Pyrophosphatase 1 (dCTPP1). Pyrcoumin wirkt der bisher unbekannten Wechselwirkung von dCTPP1 mit der Ubiquitincarboxy‐terminalen Hydrolase (USP7) entgegen.